The invention relates to a method for visualizing spatially resolved measurement results, wherein a measuring unit establishes a spatially resolved measurement result of an object and a false-color image is obtained from the spatially resolved measurement result.
The invention furthermore relates to a measuring arrangement, comprising a measuring unit, which is configured to capture a spatially resolved measurement result in a first solid angle region, a conversion and data-processing unit, which is configured to obtain a false-color image from the spatially resolved measurement result, and a representation unit for outputting the false-color image.
Here, a spatially resolved measurement result of an object is understood to mean any two-dimensional arrangement of measurement values, with the arrangement describing an assignment of the individual measurement values to different spatial regions of the object. Examples of spatially resolved measurement results include thermal images, X-ray images, sound images.
It is known to record such measurement results by contactless measurements from the distance.
It is often desirable to provide the simultaneous or almost simultaneous visualization of the measurement results in a manner that is as clear and obvious as possible.
The previous procedure has been that of measuring the property using the measurement instrument and converting it into a false-color image, which is then generally shown on a small display or stored. Thus, the user is forced to alternate his attention between the display and then the real object again and he must attempt in his imagination to bring the image on the display into correspondence with the real object.
Here, a false-color image is understood to mean any two-dimensional representation of a spatially resolved measurement result, in which the individual measurement values are respectively assigned a color and/or brightness value in a color or brightness code.
There are many properties of objects which are invisible. One such property is the surface temperature or the black-body radiation, which, according to Planck's law, is emitted by every body with a finite temperature. Thermography describes the contactless measurement of the surface temperature and the conversion of the measurement into a spatially resolved image, which is typically displayed as a false-color representation on an indication instrument (display or monitor). A commonly used (but arbitrary) color coding is the use of red and yellow for warm and hot regions, and of blue and black for cold regions.
Thermographic measurements have many application options; a few examples:                examining buildings in order to identify defects in the thermal insulation        seeking leaks in water pipes that run within the floor or a wall and are therefore invisible and inaccessible        detecting mold infestation in buildings        measuring plants and machines in order to find defects such as leaks or poor mechanical or electrical connections (if these can be detected by a temperature difference)        measuring electronic circuits to detect faults such as poor contacts or non-functioning components        seeing residual heat in forensics, at points where a person was present        identifying inflammation foci in medical examinations; this is also often used in the field of veterinary medicine.        
In these applications, the measured temperature differences are often only of the order of a few tenths of a degree, which can be captured well by the cameras.
Here, thermographic images are typically recorded by a suitable camera or a scanner, and are subsequently processed in a report in which the images recorded by the thermographic camera are printed and provided with appropriate explanations. A disadvantage of such a report always is that it is difficult to orient oneself on the basis of the usually relatively low-resolution images. Furthermore, this mode of operation is disadvantageous in that time passes between the measurement using the thermographic camera and the completion of the report: it may take days or weeks until a report has been completed. This increases the risk of incorrect assignments of the images to the observed objects.
In particular, the creation of a report is not suitable in the case of urgent and time-critical measurements for finding defects or leaks in e.g. a water pipe or heating pipe with a rupture within a wall because further damage is made while the report is being created. It is important and helpful to both the owner of the building and the skilled worker who should fix the problem to know the point as quickly and directly as possible in order to be able to resolve the problem in a quick and targeted fashion and, in the process, cause as little additional damage as possible, for example as a result of ripping open relatively large areas of the wall. Moreover, in the case of printed images in a report, it is difficult to re-localize the precise position (of the damage) on the object in situ as a result of the often low-resolution images in the report.
The low resolution of thermographic images can also be seen as a system-typical disadvantage of thermographic cameras per se.
A further feasible field of application lies in forensics or forensic sciences, with other wavelength regions also being considered in this case: the range of ultraviolet radiation (wavelength less than approximately 400 nm) or radiation in the range of near infrared (wavelength greater than approximately 700 nm up to 1400 nm). In the case of forensic analyses of a crime scene by investigative and law-enforcement authorities, invisible leads are sought after and the aforementioned wavelength ranges can provide important clues. There are sensors and cameras which can record images in these invisible wavelength ranges and thus, for example, make it possible to identify traces of blood.
Since, in contrast to the thermographic application above, the objects observed in this case typically are not active emitters, work must optionally be undertaken with an additional, suitable radiation source and the observed solid angle region must be correspondingly illuminated; the reflected light is then measured in this case.
Here, the current prior art is once again a similar mode of operation as in thermography: the images can be recorded and stored and then integrated into reports with a time delay. In the case of the court hearing, this is surely necessary and also sufficient. However, the time delay is a significant disadvantage for ongoing investigations because such leads should be visible as clearly, directly and instantaneously as possible.
The disadvantage in this course of action lies in the fact that there is a relatively long time (hours/days or weeks) between the measurement and the availability of the report and hence between the report and possible (preventative) measures.
A further disadvantage lies in the fact that a representation on a small display is not immediately and easily identifiable for a plurality of persons such as e.g. an investigation team. Moreover, the representation is indirect and the identifiable image on the display must be made to be congruent with the real objects in the imagination.
A further disadvantage lies in the fact that such reports may, under certain circumstances, be difficult to understand for e.g. a skilled worker who should undertake repairs at a specific point and hence make carrying out the repairs more difficult because it is unclear precisely where each recording was created: in the case of detailed recordings of interior spaces such as e.g. walls, room corners, radiators and roller shutter casings there by all means is the risk of subsequent mix-ups.
Even in the case of the examination directly in situ with an appropriate camera the images are still indirect because they can only be seen on a—usually small—monitor and this relates precisely to measured parameters that are invisible. Whoever has worked with a corresponding instrument knows that it can by all means be difficult to find precisely the correct point on e.g. an object like a wall under which one according to the displayed measurement results on the monitor believes there to be a defect like a broken water pipe.
The prior art furthermore includes the representation instruments that are used by methods according to the invention; these are distinguished by at least the following properties:                the representation instrument has a suitable input for the signal which was measured by the measuring instrument and which represents, in a spatially resolved fashion, the measured property in the solid angle as e.g. false-color image        the representation instrument projects a spatially resolved image in a specific solid angle region in the visible wavelength range of the light (i.e. in the wavelength range between approximately 400 nm and 700 nm).        
Examples include beamers or projectors, as also used for the magnified representation of image data such as e.g. presentations or else films by means of computers and as are commercially available in large numbers and in many different embodiments. A problem of instruments that use a conventional, incoherent light source such as e.g. a halogen lamp is that, in the envisaged application, one can generally not make the assumption that a planar surface is being examined. According to classical optics, such instruments, due to their underlying principles, usually only have a small distance range in which a sharp image representation is possible (small depth of field) and hence there is the problem in an application at an arbitrary observation angle to a plane or in the examination of non-planar objects that parts of the image are usually out of focus.
Thus, in principle, a better option for the representation are laser-based instruments, which are already available in small quantities (state: December 2009) and are provided as large film projectors or as miniaturized projectors for application in mobile electronic instruments such as cellular telephones. As a result of the very small beam-widening property of the laser beam, there is a sharp representation independently of the projection distance.
This is particularly advantageous if the application within the meaning of the invention is dynamic and the observed solid angle region and the location and the spatial orientation of the combined measurement and representation are changed quickly by the user.
Furthermore, the laser-based beamers are particularly small and light and they can, for example, be operated by batteries, which advantageously eases the energy supply during the use according to the invention.